The nss_ldap package contains the nss_ldap and pam_ldap modules. The
nss_ldap module is a plug-in which allows applications to retrieve
information about users and groups from a directory server. The pam_ldap
module allows PAM-aware applications to use a directory server to verify
user passwords.

A race condition was discovered in nss_ldap which affected certain
applications which make LDAP connections, such as Dovecot. This could cause
nss_ldap to answer a request for information about one user with
information about a different user. (CVE-2007-5794)

In addition, these updated packages fix the following bugs:

* a build error prevented the nss_ldap module from being able to use DNS to
discover the location of a directory server. For example, when the
/etc/nsswitch.conf configuration file was configured to use "ldap", but no
"host" or "uri" option was configured in the /etc/ldap.conf configuration
file, no directory server was contacted, and no results were returned.

* the "port" option in the /etc/ldap.conf configuration file on client
machines was ignored. For example, if a directory server which you were
attempting to use was listening on a non-default port (i.e. not ports 389
or 636), it was only possible to use that directory server by including the
port number in the "uri" option. In this updated package, the "port" option
works as expected.

* pam_ldap failed to change an expired password if it had to follow a
referral to do so, which could occur, for example, when using a slave
directory server in a replicated environment. An error such as the
following occurred after entering a new password: "LDAP password
information update failed: Can't contact LDAP server Insufficient 'write'
privilege to the 'userPassword' attribute"

This has been resolved in this updated package.

* when the "pam_password exop_send_old" password-change method was
configured in the /etc/ldap.conf configuration file, a logic error in the
pam_ldap module caused client machines to attempt to change a user's
password twice. First, the pam_ldap module attempted to change the password
using the "exop" request, and then again using an LDAP modify request.

* on Red Hat Enterprise Linux 5.1, rebuilding nss_ldap-253-5.el5 when the
krb5-*-1.6.1-17.el5 packages were installed failed due to an error such as
the following:

When recursively enumerating the set of members in a given group, the
module would allocate insufficient space for storing the set of member
names if the group itself contained other groups, thus corrupting the heap.
This update includes a backported fix for this bug.

Users of nss_ldap should upgrade to these updated packages, which contain
backported patches to correct this issue and fix these bugs.

4. Solution:

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.